limpiar :: [Char] -> [Char] -> [Char]
limpiar [] ys = []
limpiar (x:xs) ys = if x `apareceEn` ys then limpiar xs ys else x : limpiar xs ys where apareceEn = elem
      
todosIguales :: [Int] -> Bool
todosIguales [] = True
todosIguales (a:[]) = True
todosIguales (a:b:xs) = (a == b) && todosIguales (b:xs)